There must be a great battle going on inwardly all the time until Self is realized.

 (from "Conscious Immortality"):

Question. Why is it sometimes I find concentration on the Self so easy, and at other times hopelessly difficult?

Ramana Maharshi:. Because of vasanas.

But really it is easy, since we are the Self. All we have to do is to remember that.

We keep on forgetting it, and thus think we are this body, or this ego.

If the will and desire to remember Self are strong enough, they will eventually overcome vasanas. There must be a great battle going on inwardly all the time until Self is realized. This battle is symbolically spoken of in scriptural writings as the fight between God and Satan. In our sruti [Vedic revelation] it is a Mahabharata war, where the asuras represent our bad thoughts and the devas our elevating ones.